Inhalation bioaccessibility, health risk assessment, and source appointment of ambient PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) in Caofeidian, China

The inhalation bioaccessibility of polycyclic aromatic hydrocarbons (PAHs) is significant for accurately assessing the health risks posed by PM_2.5-bound PAHs. In this study, 96 PM_2.5 samples from Caofeidian, China, were investigated for PM_2.5-bound PAH source appointment and bioaccessibility assessment during four seasons. PAH₁₈ potential sources were identified by positive matrix factorization. The inhalation bioaccessibility of PAH₁₈ was investigated by simulated epithelial lung fluid extraction. The incremental lifetime cancer risk (ILCR) model was subsequently used to evaluate the carcinogenic risk posed by PM_2.5-bound PAHs in children, teenagers, and adults. Four potential sources of PM_2.5-bound PAH₁₈ were identified: industry emissions (44%), petroleum volatilization (30%), vehicle emissions (15%), and coal combustion (11%). The average inhalation bioaccessibility of PAHs ranged from 17.8% (dibenzo [a,h] anthracene) to 67.9% (fluorene). The ILCR values for children and teenagers were lower than the acceptable levels (10^-6) in the four seasons considering inhalation bioaccessibility. However, the ILCR value of adults was higher than the threshold in winter (1.26 × 10^-6). Source identification suggested that reducing industrial pollution was the primary measure for controlling PM_2.5-bound PAHs in Caofeidian. Additionally, the inhalation bioaccessibility of PM_2.5-bound PAHs was evaluated to precisely estimate the health risks caused by PAHs.

Inhalation bioacessibility and absorption of polycyclic aromatic hydrocarbons (PAHs) in indoor PM2.5 and its implication in risk assessment

Inhalation bioaccessibility of polycyclic aromatic hydrocarbons (PAHs) in PM_2.5 was assessed in numerous studies, however, the lung cell uptake and penetration of PAHs was seldom taken into account in risk assessment. In the present study, eighteen indoor PM_2.5 samples collected from Guangzhou, China were analyzed for the inhalation bioavailability of PAHs combining the inhalation bioaccessibility and cell absorption of PAHs. Two simulated epithelial lung fluid mimicking the healthy condition (as represented by gamble's solution (GMB), pH = 7.4) and the inflammatory condition (as represented by artificial lysosomal fluid (ALF), pH = 4.5) were employed to evaluate the inhalation bioaccessibility. The results indicated that the bioaccessibility of PAHs under the inflammatory condition (1.28%-87.7%) was higher than that under healthy condition (0.88%-87.6%). Naphthalene, phenanthrene, pyrene and benzo[a]pyrene were selected for absorption assay of lung epithelial cells (A549). The absorption rate of PAHs ranged from 64.7 to 90.7% and it was inversely proportional to the number of aromatic rings. Taken together, the inhalation bioavailability based on the bioaccessibility of PAHs and the lung cell absorption ratio ranged from 9.9 to 56.9% under the healthy state, from 12.7 to 65.6% under inflammatory condition. The correction parameter (F_c) was thus established and can be used to improve the risk assessment of human exposure to PAHs via PM_2.5 inhalation in future work.